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Extraction of Scandium from Critical Elements-Bearing ...

In direct acid leaching, the rhomboclase phase is formed during acid leaching and co-precipitate scandium. Indeed, direct leaching consumes less energy than acid baking. For this reason, different approaches might be explored. Alkan et al. studied silica gel suppression on H 2 SO 4 leaching with hydrogen peroxide (H 2 O 2).

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Leaching (metallurgy) - Wikipedia

Leaching is a process widely used in extractive metallurgy where ore is treated with chemicals to convert the valuable metals within into soluble salts while the impurity remains insoluble. These can then be washed out and processed to give the pure metal; the materials left over are commonly known as tailingspared to pyrometallurgy leaching is easier to perform, requires less energy and ...

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Acid Mine Drainage - Earthworks

Definition of acid leach. Metallurgical process for dissolution of metals by means of acid solution. Examples include extraction of copper from oxide- or sulfide-bearing ore and dissolution of uranium from sandstone ores. Acid leaching can occur on heap-leach pads or in situ.

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(PDF) Atmospheric acid leaching of nickel laterites review ...

This review examines the atmospheric leaching (AL) of nickel laterite ores with sulphuric acid, specifically the limonite, smectite (clay) and saprolite fractions. The kinetics and mechanism of leaching of the key minerals are reviewed together with

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In situ leach - Wikipedia

In-situ leaching of copper was done by the Chinese by 977 AD, and perhaps as early as 177 BC. Copper is usually leached using acid (sulfuric acid or hydrochloric acid), then recovered from solution by solvent extraction electrowinning (SX-EW) or by chemical precipitation.Ores most amenable to leaching include the copper carbonates malachite and azurite, the oxide tenorite, and the silicate ...

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Pressure Oxidation - Caldera Engineering

Pressure Oxidation (POX) is a process used to extract gold, copper, zinc, molybdenum, and uranium from refractory ore bodies. The POX process utilizes elevated temperatures (roughly 230 degrees Celsius), elevated pressures (roughly 35 bar or 510 psi), and oxygen to liberate the minerals from refractory ores. POX has been used since 1985 when it ...

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Intensification of Sulfuric Acid Leaching of Altered ...

A new method of altered ilmenite processing has been studied. In this method, sulfuric acid is used as the reaction medium of the process, and fluoride ions are activators of the dissolving process of the rutile part of the ore raw material. The regression model of the sulfate–fluoride leaching process was developed and analyzed by using the response surface method of 23 matrix.

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Innovations in Copper: Mining & Extraction: Producing ...

Whether by bioleaching or conventional acid leaching, operating costs for heap leaching for currently operating or planned projects range between US$0.34 and US$0.60. 27 An example of this is Codelco-Chile's operation, Radomiro Tomic, located near Calama, Chile.

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What is Acid Rain? | US EPA

Acid rain results when sulfur dioxide (SO 2) and nitrogen oxides (NO X) are emitted into the atmosphere and transported by wind and air currents.The SO 2 and NO X react with water, oxygen and other chemicals to form sulfuric and nitric acids. These then mix with water and other materials before falling to the ground. While a small portion of the SO 2 and NO X that cause acid rain is from ...

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The Leaching of Hematite in Acid Solutions | SpringerLink

The leaching rate of hematite was seen to be first order with respect to hydrogen ion activity, a(H +), in hydrochloric acid or perchloric acid solutions, with or without the addition of common salts, while the rate was of a half order in sulfuric acid solutions with or without the addition of sodium sulfate. A theoretical analysis showed that ...

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US Patent for Acid leaching of rare earth minerals Patent ...

FIG. 3 is a graph illustrating extraction results for acid treated 6 and water leach embodiments using various acid additions, under conditions of: acid treatment at 200° C. of 6 mesh material for 2 h followed by 24 water leach. FIG. 4 is a graph illustrating water leach extraction of rare earth elements with time.

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Leaching Meaning - Definition, Types, Advantages and ...

4. Acid Leaching. As the first stage of extraction of base metals, acid leaching is often used, especially in the case of copper, for which mineral acids such as HCl, H 2 SO 4 or HNO 3 are used in conjunction with H 2 O 2, a powerful oxidant that enhances the acid's leaching efficiency.

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US3809549A - Acid leaching of lateritic ore - Google Patents

nickel values are acid leached from nickeliferous oxide orres by forming an aqueous slurry of ore and pyrites in an autoclave and oxidizing the pyrites at a temperature between about 200*c. and 260*c. to provide a sulfuric acid solution for selectively leaching the nickel values contained in the nickeliferous oxide ore without encountering undue scale formation on the autoclave walls and in ...

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In Situ Leach Mining (ISL) of Uranium - World Nuclear ...

Acid leaching gives higher uranium recovery – 70-90% – compared with 60-70% for alkaline leach, and operating costs are about half those of alkaline leach. Techniques for ISL have evolved to the point where it is a controllable, safe, and environmentally benign method of mining which operates under strict operational and regulatory controls.

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What is leaching? | National Critical Zone Observatory

This oxidation caused by leaching is one of the main drivers of acid mine drainage! Once leaching of iron and other previously unoxidized metals begins, it is difficult to reverse the resulting acid mine drainage (Check out this article on acid mine drainge by the BBC). Leaching may also occur high above soil, regolith, and rock, in the tree tops.

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A STUDY OF LEACHING OF COPPER OXIDE ORE BY SULPHURIC ACID

A required amount of 75 g/L. sulphuric acid solution was used and 5 g of the ground copper oxide ore with a solid to liquid. ratio of 13%. Leaching parameters such as leaching time from 0.25 – 4 ...

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High Pressure Acid Leach - Caldera Engineering

High Pressure Acid Leach (HPAL) is a process used to extract nickel and cobalt from laterite ore bodies. The HPAL process utilizes elevated temperatures (roughly 255 degrees Celsius), elevated pressures (roughly 50 bar or 725 psi), and sulfuric acid to separate nickel and cobalt from the laterite ore. HPAL has been used since 1961 when it was ...

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Chemical Leaching of Sulfidic Mining Waste, Plombières ...

Leaching of yellow tailings with H 2 SO 4 solubilized a significant amount of Fe (1376 mg L −1) and leached 28% of Zn on average (0–50%). Similarly to the results of metallurgical wastes and brown tailings, leaching with sulfuric acid caused the formation of an anglesite precipitate in the solid residue (Table 10S).

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Review of Environmental Impacts of the Acid In-situ Leach ...

In response to claims that acid in-situ leaching (ISL) mining of uranium in South Australia and disposal of wastes will contaminate groundwaters, the State Government requested the EPA to conduct an independent review of the environmental impacts of the mining process.

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A Canadian Scientist Explains How Acid Rain is Still ...

What Has IISD-ELA Taught Us About Acid Rain? In order to mimic the acidity of the rain that was falling on freshwater ecosystems at the time (in the mid-1970s), Schindler and his team introduced minute amounts of sulfuric acid into an experimental lake (Lake 223) in order to reduce the pH (i.e., acidify the lake) from about 6.8 to about 5.0 ...

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US9732400B2 - Autoclave apparatus used during high ...

In an autoclave apparatus for a high-pressure acid leaching process which advances leaching by stirring heated and pressurized material slurry and sulfuric acid by stirrers in compartments in an autoclave main body of a plurality of compartments, transfers slurry from an upstream side compartment to a downstream one to advance leaching, liquid flow ports for slurry transfer that open and close ...

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Heap Leaching - Mineral Processing & Metallurgy

heap leaching of copper ores leaching oxidized copper ores effect of strength of acid in leaching. Heap Leach Pad Design. Because flow is downward in percolation leaching, the leach pad is the most important element of the solution containment system.The leach pad supports the ore heaps, collects solution flowing through the heaps, transports the solution laterally to drainage pipes or …

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Acid Leaching - Copper Ore Treatment Method

Acid Leaching Process Flowsheet. The method of dissolution by sulfuric acid and ferric sulfate with chemical precipitation by means of scrap or sponge iron appears to offer the best potential for wide application and low costs. Its basic chemistry is not complex but its economic application is dependent on handling of materials and solutions by ...

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Sulphide Leaching - Mineral Processing & Metallurgy

Acid leaching: Dilute acids dissolve some metal sulphides with liberation of H 2 S, e.g. ZnS + 2H+ ^ Zn 2+ + H2S. Three types of sulphides can be encountered. Completely soluble sulphides: Zns, CoS, NiS, FeS. Slightly soluble, e.g. FeS 2.

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US2916357A - Nitric acid leaching process - Google Patents

US2916357A US694933A US69493357A US2916357A US 2916357 A US2916357 A US 2916357A US 694933 A US694933 A US 694933A US 69493357 A US69493357 A US 69493357A US 2916357 A US2916357 A US 2916357A Authority US United States Prior art keywords iron solution parts nitric acid dissolved Prior art date Legal status (The legal status is an assumption and is not a legal …

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Conventional Uranium Mills | NRC.gov

In most cases, sulfuric acid is the leaching agent, but alkaline solutions can also be used to leach the uranium from the ore. (In addition to extracting 90 to 95 percent of the uranium from the ore, the leaching agent also extracts several other "heavy metal" constituents, including molybdenum, vanadium, selenium, iron, lead, and arsenic.)

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Definition of acid leach

Definition of acid leach. Metallurgical process for dissolution of metals by means of acid solution. Examples include extraction of copper from oxide- or sulfide-bearing ore and dissolution of uranium from sandstone ores. Acid leaching can occur on heap-leach pads or in situ.

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TCLP Questions | Test Methods | Wastes | US EPA

Increasing the acid strength of the leaching fluid to leach a larger amount of any of the constituents changes the scenario that the test was designed to simulate. Therefore, one would have to consider changing the numerical limits for the constituents listed in the toxicity characteristic too.

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Acid Soils Nitrogen Leaching and Buffering Capacity ...

Soil acidity compromises agricultural output in tropical acid soils. Highly weathered tropical acidic soils are characterized by low pH, organic matter, nutrient availability, but high aluminium and iron concentration. Hence, N availability becomes a limiting factor in such soils. To this end, these leaching and pH buffering capacity studies were conducted to determine the effects of co ...

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US4410498A - Acid leaching of nickel from serpentinic ...

US4410498A US06/312,252 US31225281A US4410498A US 4410498 A US4410498 A US 4410498A US 31225281 A US31225281 A US 31225281A US 4410498 A US4410498 A US 4410498A Authority US United States Prior art keywords nickel leaching ore acid solution Prior art date Legal status (The legal status is an assumption and is not a legal conclusion.

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